Self-locking relay



Dec. L. W BURCH SELF-.LOCKING RELAY Filed Dec. e, 1944 INI/EN TOR. VA/00N n( @upc/71 Patented Dec. 25, 1,945

UNITED STATES PATENT OFFICE l SELF-LOCKING RELAY Lyndon W. Burch, Pelham, N. Y. Application December B, 1944, Serial No. 567,290

Claims. (Cl. 20G-87) (Granted. under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

This invention relates to electrical relays, and more particularly, to relays adapted to be selflocking in both contact open and contact closed positions.

The principal object of the invention is to provide a simple and durable structure for locking the armature of a relay against shock or accidental motion in open or closed position.

A further object of the invention is to provide a relay structure differing from conventional structures in that the use of a relatively heavy spring and a consequently large electromagnet is eliminated.

For the attainment of these objects, I utilize in conjunction with a relay armature a pair of columnarly-arranged leaf 'springs of. arcuate transverse section and anarrangement thereof whereby one of said springs is adapted to buckle when the armature is moved responsive to energization of an electromagnet, the other spring assuming a straight position to substantially lock the armature in contact closed position. Conversely, when the electromagnet is deenergized, the springs assume alternate positions, the previously buckled spring straightening out and substantially locking the armature in contact open position and the previously straight spring then being caused to assume a buckled position. Due to the arcuate transverse sections provided, certain novel eiects are obtained, as will be apparent from the following detailed descriptionwith reference to the appended drawing, in which:

Fig. 1 shows a relay constructed in accordance with the principles disclosed herein with the contacts in open position;

Fig. 2 shows the relay of Fig. l with the contacts in closed position; and

Fig. 3 is a section through 3-3 of Fig. 2 drawn to an exaggerated scale for purposes of illustration.

The structure disclosed on the drawing comprises a frame member l to which is secured an electromagnet 2 and a post 3. The post 3 comprises two magnetically permeable members 3a and '3b mechanically fastened together at their e sides by a pair of nonmagnetic plates I, of brass` or the like, whereby members 3a and 3b are magnetically isolated from each other to form a gap between the bent over portions 3c and 3d. Member 3b pivotally supports at 5 an armature 6 which extends into the magnetic eld of electro-1 magnet 2 and is adapted to be attracted thereto. The armature 6 is provided at an outer extremity with a contact button iB which is adapted to engage another contact button ii secured to frame l, upon energization of electromagnet 2, for the purpose of closing an electrical circuit. A pair oi leaf springs I4 and i5 of arcua transverse section are provided columnarly disposed on opposite sides of the post il and arranged to abut between suitably-spaced sockets 2li and 2l provided on armature 6, asshown. Leaf spring i5 is constructed stiffer than spring it for a purpose to be hereinafter described. The sockets ttl and 2l are secured to armature t through the medium of spring strips 23 and 2d, respectively, and are adjustable relative to armature 6, to compensate for wear or looseness, by means of the screw and lock nut assemblies 2l and 28, respectively. A link 30 mechanically connecting the center portions of springs ii and i5 is provided passing through the magnetic gap between portions 3c and 3d.

A soft iron armature, such as a washer 32, is provided secured on link t@ adjacent spring i5, capable of being attracted towards portions 3c and 3d when electromagnet 2 is energized, since a magnetic circuit is formed, as shown by the dotted line. Ordinarily, when electromagnet 2 is deenergized, the greater stiiness of spring l5 compared to spring ill causes buckling oi the latter, as will be understood by comparison of these members in Figs. l and 2, spring ill being shown as buckled in Fig. 1 but straight in Fig. 2. Spring i5, when straight (Fig. l), serves to lock armature 6 in contact open position.

When electromagnet 2 is energized (Fig. 2), thereby pulling the adjacent portion of armature 6 in a clockwise direction, and simultaneously, pulling washer 32 toward portions 3c and 3d, a

' buckling of leaf spring i5 is caused, due chiefly to the latter pulling effect, and contact is closed between ill and li. Owing to the simultaneously increased distance between sockets li and 2li and to the thrust exerted by link til as spring i5 is buckled, spring N assumes a straightened positionjsubstantially locking the armature 8 in contact closed position. When electromagnet 2 is deenergized, spring i5, due to its inherent resiliency, again assumes a straightened position, and, by exerting a pull through link 3U, causes buckling of spring lll, the conditions shown on Fig. l then being restored. As shown in Fig. 3, springs I4 and l5 have their concave sides preferably, but not necessarily, facing towards post 3 so that their directions of buckling will be as indicated in Figs. 1 and 2, since the resistance to buckling is ordinarily less in the direction of ccncavity than, in the direction of convexity.

Ari important aspect of providing springs with arcuate transverse sections resides in the comparative resistances offered when straight and when buckled. Once the comparatively high resistance to buckling ci an arcuately sectioned spring has been overcome, the force necessary to maintain it in buckled condition is relatively small. For this reason spring tl will provide a relatively high resistance to maintain amature CFI t substantially locked in contact closed position,

although after being buckled (upon deenergization of electromagnet 2) very little force need be exerted to maintain it in buckled condition. Likewise, when electromagnet 2 has been energized suiciently to overcome the resistance to buckling of spring i5, by means of the displacement of washer 32, the same amount of energize.- tion need not be maintained to hold spring i5 in buckled condition, so that an appreciable drop in energization current may be realized Without opening the circuit between contacts i and il. The contact pressure will accordingly remain substantially constant despite a lessening of the energizing current. In practice it has been found feasible to provide springs is and I5 with circular transverse sections, although it will be understood that other shapes may be devised Without departing from the spirit oi the invention.

It will be appreciated that I have disclosed a principle and an operable structure for a relay which is not only self-locking but which eliminates the use of a relatively heavy spring and the consequently large electromagnet ordinarily required to overcome the resistance thereof. The lightened and more economical structure resulting is considered to be an improvement over conventionally constructed relays and I claim:

l. In an electrical relay, frame means adapted to be secured relative to an electromagnet, a relay armature and means pivotally securing said armature to said frame means,l s aid armature having a portion thereof extending into magnetic coaction with said electromagnet andadapted to be pivotally moved relative to-said support means to close a circuit between a pair of electrical contacts upon energization of said electromagnet, and spring means adapted to abut between said armature and said frame means, and means whereby. said spring means is caused to buckle when said electromagnet is energized, said spring means being adapted to be substantially straight when said electromagnet is deenergized, the arrangement being such that said spring means ofiers initially high resistance to buckling when straight, but low resistance to maintenance of buckled position after the initial high resistance has been overcome.

2. In an electrical relay, frame means adapted to be secured relative an electromagnet, a support means secured relative to said frame means, an armature and means pivotally securing said armature to said support means, said armature having a portion thereof extending into magnetic coaction with said electromagnet and adapted to be pivotally moved relative to said support means to close a circuit between a pair of electrical contacts upon energzation of said electromagnet, a pair of spring means adapted to abut between said armature and said frame means and means whereby one of said spring means is adapted to buckle when said eleetromagnet is energized and to be substantially straight when said electromagnet is deenergized, the other of said spring means being adapted to buckle when said electromagnet is deexiergized and to be substantially straight when said electromagnet is energized, whereby one of said springs is operative to substantially lock said armature in contact closed position and the other of said spring means is operative to substantially lock said armature in contact open position.

3. In an electrical relay as set forth in claim 2, including means mechanically connected to one of said springs, said means being adapted to be displaced by magnetic force when said electromagnet is energized, to cause buckling of said one spring.

4. In the structure as set forth in claim 2, wherein said spring means are disposed on opposite sides of said means pivotally securing said armature to said support means whereby pivotal movement of said armature in contact closing direction or contact opening direction is operative to buckle one of said springs.

5. In the structure as set forth in claim 2, wherein said spring means comprise columnar leaf springs.

6. In the structure as set forth in claim 2, wherein linkage means is provided interconnecting said springs and operative to transmit buckling force between said springs.

7. In the structure as set forth in claim 2, wherein one of said springs is provided with a stiffness substantially greater than the other of said springs and means providing for transmission of said buckling torce from said stifer spring to said other spring whereby straightening or" said stiller spring is operative to buckle said other spring.

8. In the structure as set forth in claim 2, wherein said springs are of arcuate transverse section and disposed on opposite sides of said pivotal securing means, one of said springs being substantially stiffer than the other of said springs and linkage means interconnecting said springs whereby straightening of said` stiffer spring is operative to buckle said other spring.

9. In the structure as set forth in claim 2, wherein linkage means is provided interconnecting said springs and operative to transmit buckling orce between said springs, said linkage means comprising a substantially straight link having extremities secured to the substantially central portions of said springs and of such length rel.- ative the distance separating said springs as to provide buckling of one spring when the other spring is substantiall;7 straight.

l0. In the structure as set forth in claim 2, including means mechanically connecting said springs, one of said springs being provided with stiffness greater than the other spring, whereby straightening of said stiffer spring is operative to buckle said other spring. e

Il. In the structure as set forth in claim 2, wherein said spring means comprise columnar leaf springs of arcuate transverse section and have their concave sides facing in opposite directions.

12. In the structure as set forth in claim 1, whereinsaid means for causing said lspring means to buckle comprises armature means mechanically connected to said spring means and displaceable by magnetic force upon energization of said relay armature.

13. In the structure as set forth in claim 2 14. In Van electrical relay, Van electromagnet 4 having a. magnetically permeable core, an armature, said armature being displaceable relative to said core, means for pivotally supporting said armature comprising a support including two magnetically permeable members in spaced'relation with a gap therebetween, one of said members being disposed so as to provide a magnetically permeable path with said amature and the other of said members being' disposed so as to .provide a magnetically permeable path with said core, spring means disposed to bias said armature away from said core, a magnetically permeable member connected to said spring means and disposed adjacent said gap, said springmeans being adapted to. be buckled to substantially overcome the biasing action thereof by displacement toward said gapof said lastnamed magnetically permeable member due to a magnetic circuit through said core, said armature,`and the gap between the members comprising said armature support means, when said electromagnet is energized.

15. In the structure as set forth in claim 14, including a second spring means cooperating with said armature and disposed for biasing said armature toward said core, and linkage means mechanically connected between said two spring means, said first spring means being stiier than said second spring means, whereby said first spring means is operative to buckle and substantially remove the bias of said second spring means when said electromagnet is deenergized.

` LYNDON W. BURCH. 

